It is well known that many dangerous communicable diseases are spread through contacting the body fluids of an infected person. After use of a syringe, residual body fluids are likely to remain on or within the syringe needle. For this reason, syringes are typically intended for a single use only. In order to be handled safely after use, the needle of a syringe must be covered to prevent it from accidentally stabbing a person who is, for example, collecting the syringe for disposal, thereby releasing residual body fluids into such person. Typically, a protective cap is provided with the syringe, which after use of the syringe can be used to cover the tip of the needle. However, it sometimes happens that persons attempting to cap a used needle miss the cap and accidentally stab themselves, resulting in potential exposure to communicable diseases.
Accordingly, it is desirable to provide a syringe wherein the needle can be retracted into the syringe following use. Syringes including retractable needles wherein the retraction of the needle is accomplished by means of pneumatic actuation have been developed, as exemplified by U.S. Pat. No. 5,868,713 to Klippenstein and U.S. Pat. No. 7,811,259 to Klippenstein, both of which are incorporated by reference herein.
Syringes utilizing pneumatic actuation must have some mechanism for causing the pneumatic activation. In the syringe designs described in U.S. Pat. Nos. 5,868,713 and 7,811,259, the mechanism for causing the pneumatic activation is a gas release cell that contains a compressed propellant, and is ruptured at an appropriate point in time to release compressed propellant and retract the needle within the syringe. A design for gas release cells for use in such devices that can be reliably and rapidly manufactured in an automated, cost-effective manner and easily assembled into the finished device in an automated fashion has not heretofore been available.
There remains a need for gas release cells that can retain compressed propellant for release at a desired time, which can be reproducibly and rapidly manufactured, and/or which can be easily assembled into a finished medical device, including pneumatically actuated retractable-needle syringes such as those described in U.S. Pat. Nos. 5,868,713 and 7,811,259.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.